Semiconductor components include external contacts that allow electrical connections to be made from the outside to the integrated circuits contained on the components. A semiconductor die, for example, includes patterns of bond pads formed on the face of the die. Semiconductor packages, such as chip scale packages, also include external contacts. One type of semiconductor package includes solder balls arranged in a dense array, such as a ball grid array (BGA), or fine ball grid array (FBGA).
Typically, a component includes only one set of external contacts on either the face side (circuit side) or the back side of the component. However, it is sometimes necessary for a component to have external contacts on both sides. For example, for stacking a semiconductor package to another identical package, external contacts can be formed on the face of the package and on the back side as well. U.S. Pat. No. 6,271,056 to Farnworth et al. discloses this type of stackable package.
Interconnects configured to make electrical connections with semiconductor components also include external contacts. A wafer probe card is one type of interconnect adapted to make electrical connections between external contacts on a wafer under test, and test circuitry associated with a wafer handler. Another type of interconnect is adapted to electrically engage unpackaged dice, or chip scale packages, packaged within a test carrier. U.S. Pat. No. 5,541,525 to Wood et al. discloses this type of interconnect and test carrier.
In each of these examples, the interconnect includes external contacts for electrically engaging the external contacts on the semiconductor component. With a conventional needle probe card the external contacts comprise probe needles. With an interconnect used with a test carrier as described above, the interconnect contacts can comprise projections formed on a silicon substrate and covered with a conductive layer.
As with semiconductor components, the external contacts for an interconnect are often formed on both sides of the interconnect. For example, a probe card can include contacts on its face for electrically engaging the component, and contacts on its back side for electrically engaging spring loaded pins (e.g., “POGO PINS”) in electrical communication with test circuitry. U.S. Pat. No. 6,060,891 to Hembree et al. discloses this type of interconnect.
The present invention is directed to a method for fabricating semiconductor components and interconnects with contacts on opposing sides.